igneous
Basalt
Basalt (dominated by Plagioclase Feldspar and Pyroxene)
Hardness: 6-7 on Mohs scale; Color: Dark grey to black; Luster: Dull/earthy; Crystal structure: Aphanitic (fine-grained); Specific Gravity: 2.8–3.0
- Hardness
- 6-7 on Mohs scale
- Color
- Dark grey to black
- Luster
- Dull/earthy
Identified More igneous →
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Dark grey to black; Luster: Dull/earthy; Crystal structure: Aphanitic (fine-grained); Specific Gravity: 2.8–3.0
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or very near the surface of a terrestrial planet or a moon. It is the most common rock type in the Earth's crust (oceanic crust).
Uses & applications
Extensively used in construction for aggregate, road base, railroad ballast, and in the manufacturing of stone wool insulation.
Geological facts
Basalt is the most common volcanic rock on Earth. It also makes up most of the surface of the Moon and Mars. On Earth, Olympus Mons on Mars is a giant basaltic shield volcano.
Field identification & locations
Identify by its heavy weight (high density), dark color, and fine-grained texture where individual crystals are not visible to the naked eye. Found in volcanic regions and ocean floors.
